As the demand for water constantly grows, the water industry is embracing advanced water treatment processes for the desalination of saline water, such as seawater or brackish water, and reclamation of impaired water, such as wastewater and drainage water. Some processes that have been used to desalinate water are membrane processes such as reverse osmosis, nanofiltration, and electrodialysis, or thermal distillation. Microfiltration and ultrafiltration membrane processes are being increasingly used for surface water and wastewater treatment.
Water recovery is a major economic parameter of drinking water production. However, this parameter is typically limited in existing membrane desalination processes. In addition to limited water recovery, another drawback is that these processes are typically considered energy intensive. Membrane based systems can suffer from additional problems. For example, membrane fouling and scaling in pressure-driven membrane processes (e.g., in reverse osmosis, nanofiltration, ultrafiltration, and microfiltration) are often a major area of concern, as they can increase the cost of operating and maintaining the systems. Pretreatment of the feed water is a way of reducing fouling and scaling, but is typically expensive. An additional drawback of most membrane-based systems is that increased salt content of the feed stream typically reduces the flux of product water due to the lower osmotic potential difference between the feed solution and the permeate.
Seawater desalination has become a common practice to supply the growing demand for water in areas having access to the ocean. Shortage of portable (drinking) water in inland areas pose much more complicated challenges to water authorities, governments, and other stakeholders. Inland regions are restricted to the use of surface water, groundwater, and/or reclaimed water.
Most wastewater treatment plants use combinations of physical, biological, and chemical processes to treat wastewater before discharge to the environment or beneficial reuse. These processes have high operating and maintenance (O&M) costs, including energy and chemicals.